Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Income Taxes Disclosure [Line Items]
Operating Loss Carryforwards	$ 94.9
Equity Method Investment, Ownership Percentage	50.00%
Additional Paid-In Capital [Member]
Income Taxes Disclosure [Line Items]
Operating Loss Carryforwards	$ 94.9
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	2.5
Research Tax Credit Carryforward [Member]
Income Taxes Disclosure [Line Items]
Tax Credit Carryforward, Amount	1.7
State and Local Jurisdiction [Member]
Income Taxes Disclosure [Line Items]
Operating Loss Carryforwards	$ 17.6
Operating Loss Carryforward Of Expiration Year	2036
Tax Credit Carryforward, Amount	$ 1.1